In onshore and offshore operations such as for hydrocarbon exploration and production, application of subsea clamp connectors is very common. These connectors are applied for attachment of various subsea assemblies. Examples may be marine risers, production flow lines attached to well heads and so on.
It is also common knowledge that subsea assemblies need to be removed after the desired operation is over, or if there is some problem with the line. For that purpose, the clamp connectors securing the line need to be unlocked/released in a subsea environment. This has to be done remotely with the assistance of a ROV carrying a ROV tool.
After operation for a substantial period of time, the clamp connector may get jammed up and normal release of the connector is not possible by applying conventional torque tool. In such a case, an emergency release tool needs to be applied, which should be possible by subsea operation of the ROV.
Over the years, there has been a requirement for such emergency release tool, for release of clamp connectors, which is capable of sub sea operation when remotely applied, such that the connector is released in a safeguarded manner, ensuring proper detachment of the concerned subsea assemblies. However, significant achievement in this respect is yet to be achieved.
The present invention relates to a clamp connector emergency release tool designed for subsea operations when normal release of a clamp connector is not possible, which tool is handled and operated by a work class ROV tool able to cut around the jack screw of a clamp connector in order to open up the clamp connector.
Granted U.S. Pat. No. 5,273,376 teaches an emergency release tool for forcefully removing a marine assembly from a subsea assembly. The marine assembly has a first flange and the sub sea assembly has a second flange. The tool has a U-shaped frame which is transported and positioned between the flanges by ROV. Hydraulic means is mounted on the frame. This hydraulic means exerts pressure on the flanges when it is actuated by a hydraulic fluid. The hydraulic fluid is supplied from means located on ROV. On doing so, the hydraulic means generates a force normal to the frame and pushes the flanges apart.
From the paragraph above, it should be understood that this US patent leaves scopes of malfunctioning of the complicated arrangement and the methodology applied, which involves forcefully prying and breaking the clamps open. This requires a much larger force to be generated than cutting through the clamp. Hence, achieving the emergency release in a safeguarded manner, enabling ensured and clear release is not achieved.
US 2005145389A1 discloses a subsea well casing cutting tool comprising a casing gripper and a rotary cutter drive assembly. This merely discloses an arrangement for straightaway cutting a subsea well casing and removing it, for example, when it is abandoned. It is not directly related to sub sea emergency release of a clamp connector used for locking sub sea assemblies.
Similar comments as above are applicable in respect of granted U.S. Pat. No. 4,557,628, which discloses an apparatus and method for remotely cutting broken parts of an underwater upright structure for emergency removal of such broken parts. Hence, this also is not directly related to sub sea emergency release of a clamp connector, used for locking sub sea assemblies.
Similarly, US 2008/0304915A1 discloses a method and device for attaching a cutting assembly to a sea bed, the cutting assembly comprising a frame work for holding the object to be cut and a cutter head.
All the above prior art relate to sub sea operation and involve cutting operation including a cutter drive. None of these have the teaching of the present invention as described herein and claimed in the appended claims.